Conventionally, various light-emitting element drive devices that drive light-emitting elements such as light-emitting diodes (LEDs) are developed.
As an example of the conventional light-emitting element drive device, there is a device that drives a transistor such as a PNP transistor connected in series to the LED and supplies a constant current to the LED so as to drive the LED. Further, some of these light-emitting element drive devices have an output ground fault protection function for preventing thermal breakdown of the transistor when the anode of the LED (a connection portion to the transistor) is short-circuited to the ground (when an output ground fault occurs).
As to this output ground fault protection function, an output ground fault protection unit detects that an output voltage as an anode voltage of the LED becomes low voltage due to occurrence of the output ground fault, and a controller turns off the transistor based on a detection signal thereof so as to prevent thermal breakdown of the transistor.
Note that as an example of a conventional technique related to the above description, there is Patent Document 1.